Abstract
Abstract Background and aims Rice is prone to Cd uptake under aerobic soil conditions primarily due to the OsNramp5 Mn transport pathway. Unlike Cd, Mn availability in rice paddies decreases as redox potential increases. We tested whether increasing Mn concentrations in solution would decrease Cd accumulation in rice through competition between Mn and Cd for uptake and/or suppression of OsNramp5 expression. Methods Rice was grown to maturity under Mn concentrations that spanned three orders of magnitude (0.30 to 37 μM) that corresponded to free Mn 2+ activities of 10 –7.9 to 10 –5.0 M while free Cd 2+ activity was held as constant as achievable (10 –10.2 to 10 –10.4 M). Plant biomass and elemental concentrations were measured in roots and shoots at each stage. Fold changes in the expression of OsNramp5 , OsCd1 , OsHMA3 , OsCCX2 , and OsYSL6 genes in vegetative and grain-filling stages of rice plants were determined. Results Competition between Mn and Cd for root uptake and accumulation in shoots was observed at the highest concentration of Mn tested. OsNramp5 expression was significantly higher in rice plants at the vegetative stage compared to the grain-filling stage, while OsCd1 and OsHMA3 showed the opposite. Solution Mn concentrations previously thought to be tolerable by rice grown to the vegetative stage led to Mn toxicity as plants matured. Conclusions Mn competes with Cd during uptake into rice with OsNramp5 expression unaffected. Different translocation paths may occur for Mn and Cd within the rice plant and over the rice life cycle, with OsCCX2 correlated with shoot Cd concentration.
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Claims 8
Claim · model-written summary
Competition between Mn and Cd was observed for root uptake and shoot accumulation at the highest Mn concentration tested.
- Taxon
- Rice
Oryza sativae0 - Treatment
- highest concentration of Mn testede2
- Outcome
- root uptake and accumulation in shootse2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e2“Competition between Mn and Cd for root uptake and accumulation in shoots was observed at the highest concentration of Mn tested”
Claim · model-written summary
OsNramp5 expression was higher in rice at the vegetative stage than at the grain-filling stage.
- Taxon
- RiceOryza sativae0
- Organ / stage
- vegetative stagee4
- Gene
- OsNramp5e4
- Outcome
- OsNramp5 expressione4
- Direction
- highere4
- Comparator
- grain-filling stagee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e4“OsNramp5 expression was significantly higher in rice plants at the vegetative stage compared to the grain-filling stage, while OsCd1 and OsHMA3 showed the opposite”
Claim · model-written summary
OsCd1 and OsHMA3 expression was lower in rice at the vegetative stage than at the grain-filling stage.
- Taxon
- RiceOryza sativae0
- Organ / stage
- vegetative stagee4
- Gene
- OsCd1 and OsHMA3e4
- Outcome
- expressione4
- Direction
- lowerinferrede4
- Comparator
- grain-filling stagee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e4“OsNramp5 expression was significantly higher in rice plants at the vegetative stage compared to the grain-filling stage, while OsCd1 and OsHMA3 showed the opposite”
Claim · model-written summary
Solution Mn concentrations tolerable at the vegetative stage led to Mn toxicity as rice plants matured.
- Taxon
- riceOryza sativae5
- Treatment
- Solution Mn concentrationse5
- Outcome
- Mn toxicitye5
- Direction
- increaseinferrede5
- Qualifier
- as plants maturede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“Solution Mn concentrations previously thought to be tolerable by rice grown to the vegetative stage led to Mn toxicity as plants matured”
Claim · model-written summary
OsNramp5 expression was unaffected by Mn competition with Cd in rice.
- Taxon
- RiceOryza sativae0
- Gene
- OsNramp5e6
- Outcome
- expressione6
- Direction
- no_changeinferrede6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e6“Mn competes with Cd during uptake into rice with OsNramp5 expression unaffected”
Claim · model-written summary
Mn competes with Cd during uptake into rice.
- Taxon
- RiceOryza sativae0
- Treatment
- Mne6
- Compound
- Cde6
- Outcome
- uptakee6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e6“Mn competes with Cd during uptake into rice with OsNramp5 expression unaffected”
Claim · model-written summary
OsCCX2 is correlated with shoot Cd concentration in rice.
- Taxon
- RiceOryza sativae0
- Gene
- OsCCX2e7
- Outcome
- shoot Cd concentratione7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e7“with OsCCX2 correlated with shoot Cd concentration”
Claim · model-written summary
Different translocation paths may occur for Mn and Cd within the rice plant and over its life cycle.
- Taxon
- RiceOryza sativae0
- Compound
- Mn and Cde1
- Outcome
- translocatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rice is prone to Cd uptake under aerobic soil conditions”
e1“Different translocation paths may occur for Mn and Cd within the rice plant and over the rice life cycle”
The same questions in other papers
manganese atom · pest · Oryza sativa (rice)Positive and negative results
1 in the opposite direction
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.